KONINILIJKE AKADEMIE VAN WETENSCHAPPEN 

 TE AMSTERDAM. 



riiOCEEDINGÖ OF THE MEETING 

 of Saturday November 26tii 1898. 



(Tijiiislatcd from: A'creliig van de gewone vergadering der Wis- en Naluurkundigo 

 Afdecling vau Zaterdag 26 November 1S98 UI. VII). 



CüSTENTS: ,,IIucmatu)iüiesis in tlie placenta of Tarsi us and other mammals". By Prof. A. A. W. 

 IIvbhecht, p. 1 67. — ,,0n a Contagium vivum fluidum causing the Spot-disease of 

 the Tobacco-leaves". By Prof. M. W. Bf.ijeuinck, p. 170. — „On congealing- and 

 melting-phenomena in substances showing tautomerisni". ]!y Prof. H. W. Baichuis Uoo- 

 ZKBOOM, p. 176. — „Variation of volume and of pressure in mixing". By Prof. J. D. van 

 DKR Waals, p. 179. — „Eijuilibriums in systems of three components. Change of the 

 mixing-temperature of binary mixtures by the addition of a third component". By 

 Mr. F. A. H. ScHKElXEMAKEKS (Communicated by Prof. .7. SI. TAX Bemmelen J. p. 191. — 

 „On the accurate determination of the molecular weight of gases from their density". 

 By Prof. J. D. vax der Waals, p. 198. — „Some remarks upon the 14-monthly 

 motion of the Pule of the Earth and upon the length of its period". By Dr. E. F. tan 

 DE Saxue Bakuuyzen (Communicated by Prof. H. G. van de Saxde Bakhuizek) 

 ]). 201. — „A standard open manometer of reduced height with transference of pres- 

 sure by means of compressed gas". By. Prof. II. Ka.mermnoh Onnes, p. 213. (With 

 one plate.) 



The following papers were read : 



Zoology. — y^lladnaiopolesis In the placenta of Tdrslus and other 

 mammals^ By Prof. A.. A. W. Hubrecht. 



The various authors who have investigated in the course of the 

 last thirty years the first origin of the mammalian red blood-cor- 

 puscles have come to conclusions that are far from unanimous. 

 This can in part be ascribed to the wish to look upon the red 

 blood-corpuscles without nucleus of the full-grown mammalia as 

 morphological elements, that are equivalent with the nucleated red 

 corpuscles of the lower vertebrates and of mammalian embryos. 



12 



Proceedings Royal Acad. Amsterdam. Vol. 



